Burglar-alarm



UNITED STATES PATENT OEEICE.

CIIARLES JOHNSON, OF CHICAGO, ILLINOIS.

BURG LAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 627,192, dated June 20, 1899.

Application tiled February 19,1898. Serial No. 670,876. (No model.)

To all wwnt it may concern:

Be it known that I, CHARLES JOHNSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Burglar-Alarms, of which the following is a specification.

My invention relates to burglar-alarms and the like; and its object is to provide a simple and inexpensive but efiicient and reliable device which may be applied to doors, Windows, or elsewhere; and my invention consists in 'the features and details of construction hereinafter described and claimed. i

In the accompanying drawings, Figure lis a view in perspective, showing my device applied both to a door and to a Window and showing the bell-circuit diagrammatically; Fig. 2, an enlarged sectional elevation of a portion of a window, showing my device attached in position; Fig. 3, an enlarged sectional elevation of a portion of a door with my device attached thereto; and Figa, a detail view of the saine device shown in Fig. 3, but removed from the door, so as to show its normal position when it is not set ready to sound an alarm.

My device is adapted to be interposed in an ordinary electrical-bell circuit, and comprises a member l and also a second member 2, pivoted to each other and by whose movement the circuit may be closed and the alarm sounded. A strap 3 preferably passes over the member l and is secured thereto bya pin 4. This strap is pivoted to the member 2 upon the pin 5. The inner faces 6 and 7 of the member l may be beveled to allow such member to rock upon the other member, which is preferably iiat.

A suitable steel spring 8 is arranged between the members to normally hold them in the position shown in Fig. e. lVhile I have herein shown a flat spring, it will be understood that a spiral spring, and in fact any other suitable means, may be employed to subserve the same desired purpose. Upon the inner faces of the two members and substantially near one end are located two electrical terminals 9 and IO of the circuit, Where it may be broken when the device is set ready for action, but adapted to be caused to contact when the set position of the alarm is disturbed.

In Fig. 1 I have shown my device applied to a Window and also to a door, in Fig. 2 I have shown the particular construction of the device when applied to a Window, and in Figs. 3 and 4 I have shown its particular construction and adaptation when applied to a door or lock. The same general principles reside in both'forms, and the only difference consists in the means whereby the device maybe set or arranged for action when applied to a door or a Window. In the form for the windoW the member l is provided with a sharp point ll, which maybe forced into the Wood itself or be received by a hole specially provided therein for that purpose. In the other form the member l has a projecting piece or nose 12, While the member 2 has a pin 13. The projecting piece or nose is adapted to enter the keyhole and keep the terminals separated when the device is set, the piece 12 entering at the top of the keyhole and the pin 13 resting upon the bottom of the hole.

My devices, being constructed as hereinabove set forth, operate as follows: Considering first the form shown in Figs. 3 and 4, the ends of the members opposite the terminals are pressed together against the tension of the spring, so as to enter the keyhole 14, as clearly illustrated in Fig. 3. This operation separates the terminals and opens the circuit; but any attempt to insert a key in the lock, so as to turn the bolt, will force the alarm device out of the keyhole. The spring will then instantly snap the members into normal position, causing the terminals to contact, andv thereby close the circuit to sound an alarm and indicate that the lock is being tampered With. In the other form, where it is applied to a window, the device is laid fiat upon the sill, and after the member 1 is rocked, as shown in Fig. 2, the pin ll is forced into the sash l5 or inserted in a hole specially provided. Obviously when the sash is raised themember l will be caused to rock and cause the terminals to contact and sound an alarm and indicate that a window has been raised. It is not necessary that the device should be attached to the sash, as shown in Fig. 2, inasmuch as it may be laid upon its side, and

IOO

the raising of the sash will still cause the members to assume their normal position.

As shown in Fig. l, all the doors and windoWs may be provided with the alarm device and the circuit so run as to have acommon bell and battery. In this figure I have shown portions of electrical circuits which may be run to other Windows or doors. (Not shown.)

By means of my invention I provide a burglar-alarm Which is Very simple in its construction and positive and reliable in its operation and one capable of ready application. Furthermore, my device may be applied to a multitude of uses and may be used else- Where than for doors and Windows to indicate an alarm for any desired purpose.

Although I have described more or less precise forms and details of construction, I do not intend to be understood as limiting myself thereto,as I contemplate changes in form, the proportion of parts, and the substitution of equivalents as circumstances maysuggest or render expedient and Without departing from the spiritvof my invention.

I claiml. A burglar-alarm device for doors, WindoWs and the like, comprising, in combination with an electric-bell circuit, two members of insulating; material pivoted to each other and interposed in the circuit, electrical terminals substantially at one end of the members and adjacent to each other, and formed upon the members themselves, a spring normally holding the members closed at the electrical terminal end and open at the other end, a projecting piece upon the normally open endv of one of the members and adapted to enter a keyhole and a pin upon the similar end of the other member whereby When the device is inserted in the keyhole of a door the electrical circuit is broken but is adapted to be closed whenever the device is forced out of the keyhole and thereupon sound an alarm.

2. The combination of the member 2, the member l pivoted thereto, electrical terminals 9 and l0 upon similar ends of the members, aspring S for normaly rocking the member l. to cause contact of the terminals and projections 12 and 13 upon the ends of the members l and 2 respectively.

CHARLES JOHNSON.

Witnesses:

SAMUEL E. HEBBEN, ALLAN A. MURRAY. 

